THE TECHNOLOGIST. [March 1, 1864. 



374 THE GEMS OP AUSTRALIA. 



make one ounce troy) of 3-16 grains each. The medium value of a 

 diamond, when rough, is £2, if ot* one carat weight ; and the value of 

 diamonds of greater weight is estimated hy multiplying the square of 

 their weight in carats hy two, which gives their value in pounds sterling. 

 Example — To find the weight of a rough diamond of two carats : the 

 square of the weight 2 x 2=4 ; this multiplied hy 2=4 x 2=£8, the 

 value of a diamond of two carats. A polished diamond of the purest 

 water, well cut and free from flaws, is worth £8 ; above that weight, the 

 value is calculated by multiplying the square of the weight in carats by 

 eight. Thus : — The value of a polished diamond of two carats — 2 x 2 x 

 8=32Z. ; the value of a polished stone of three carats— 3 x 3 x 8=721., 

 and so on." Bristow, page 110. The following information is taken from 

 the work of Dr. L. Feuchtwanger, New York, 1859 :— " Diamonds are 

 found in talcose chlorite schist and in a breccia, consisting of ferruginous 

 clay, quartz pebbles, sand and oxide of iron fragments ; and also in a 

 secondary bed, accompanied by gold, platinum, topaz, beryl, tourmaline, 

 kyanite, amatoze, spinelle, corundum, and garnet. The rocks in which 

 diamonds have been recently found, consist of the itacolumite, a mica- 

 ceous sandstone, accompanied by mica-schist, accidentally traversed by 

 quartz veins. The gold, diamonds, and other fine stones are always 

 imbedded in the lower part of the alluvium." Speaking of Brazil, he 

 says, " Experience has shown the richest localities to be in Curranlinho, 

 Datas, Mendanho, &c, where the alluvial soil is from eight to twenty 

 feet thick, and is composed almost entirely of silicious sand, strongly 

 colored by argillaceous iron, which forms a species of cement of pebbles 

 of quartz, milky quartz, and itacolumite, which form a coarse pudding 

 stone, called casoelho, and which is considered by the diamond-washers 

 a sure sign of the diamond." — Pp. 188, 189. I travelled last year over a 

 vast area of formations of the above characters. I allude to the district 

 in which the diamonds have been found ; it stretches from the foot of 

 the Beechworth hills to Chiltern, and further; and in even more 

 strongly marked features between Chiltern and Butherglen. The 

 rubbish thrown out of every hole sunk by the diggers at intervals over 

 that plain was strongly marked with the above-mentioned features. 

 The gravelly hill at Northcote, and the one above Johnston street 

 bridge — out of which came the small diamond which I exhibit — are not 

 altogether without these characteristics. Mr. Anderson, of the Junction 

 Hotel, Plenty road, stopped me lately when passing, but before the 

 small diamond was found in Coilingwood, to show me quite a quantity 

 of stones — beryls and tourmalines, I think, and others that I have not 

 yet had time to study — which he had picked out of a hill at the back of 

 his house, apparently of the same formation as that at Northcote. Surely 

 it would be interesting if the Government geologists would examine, or 

 cause these formations to be examined. I understood Mr. Anderson who 

 has had much practical experience in mining, both in America and here, 

 to say that he had traced them to the granite hills above the Yan Yean. 



